1. Field of the Invention
The present invention relates to an object gripping apparatus for performing bin picking of piled works using an industrial machine such as a robot, a method of controlling the same, and a storage medium. The present invention particularly relates to an object gripping apparatus for picking works piling up irregularly on a tray while measuring their three-dimensional positions and orientations, a method of controlling the same, and a storage medium.
2. Description of the Related Art
There are many research reports about an apparatus for automatizing the part supply or assembly process by causing an industrial robot to pick works piling up irregularly on a tray. An example is Japanese Patent No. 03377465. In Japanese Patent No. 03377465, a robot performs picking by executing pattern matching using a three-dimensional model prepared in advance so as to recognize the position and orientation of a work. In Japanese Patent No. 03377465, the apparatus measures the three-dimensional position and orientation of only one work at a time. Hence, when bin-picking piled works, position and orientation measurement processing needs to be repeated as many times as the number of works stacked on the tray. To decrease the number of times of position and orientation measurement processing upon bin picking, a method of obtaining and holding the three-dimensional positions and orientations of a plurality of works by one measurement operation has been considered. In Journal of IHI technologies Vol. 48, No. 1 (2008-3), three-dimensional position and orientation recognition is done for a plurality of piled works having a complex shape.
However, when the three-dimensional positions and orientations of a plurality of works are measured at once, the measured positions and orientations of the works may vary due to interference that may occur between the robot arm and the picking target work at the time of work picking after the measurement. In this case, the work whose position and orientation have varied needs to be remeasured, resulting in time-consuming processing.
The present invention has been made in consideration of the above-described problem, and provides a technique of reducing the influence of a variation in the position and orientation of a work caused by interference upon picking.